The invention is related to an insulator on the bottom of which, axially centered and concentric with a mounting bracket, is at least one ring-shaped recess, which forms a path for the insulation leakage current. On the outside of the insulator is an electrically conducting metal cup.
Insulators with an electrically conducting metal cup on the outside, which are installed in capacitive protective fences and are exposed to extreme environmental conditions, must possess corrosion resistant electrically conducting surfaces. Protective fences in the vicinity of the ocean or in desert regions are exposed to an extremely aggressive climate and extraordinarily strong stresses, because sand, air, moisture and salt attack the surfaces of the insulator, as well as the mounting and fastening devices used with the insulators. Consequently, existing insulators often fail in exposed installations due to the corrosive effects of environmental factors.